The Gregson et al. one-parameter model (GHM) is based on the log-log form of the soil water retention curve, below the air-entry value of ψ, ln ψ =a+bln &thetas;, whereaandbare the intercept and slope, respectively. A strong linear relationship observed betweenaandbwas expressed asa=p+qb. Given this relationship, the GHM was derived as ln ψ =p+b(ln &thetas; +q). Givenpandqvalues for a soil or group of soils, only one value of the ψ(&thetas;) relationship needs to be known to calculate the only unknown parameter in the model - b, and hence, the entire ψ(&thetas;) function. Typically, &thetas; at the −33 kPa matric potential (&thetas;-33 kPa) is used as the known ψ(&thetas;) value. Here we provide a regression relationship betweenband the available water content (AWC) to estimateb, since in many cases the AWC is available in the USDA soil survey reports, whereas &thetas;-33 kPais not. Using thebthus estimated in GHM gives only slightly larger errors in calculating the water content at different potentials than when using &thetas;-33 kPa. Further we show that the intercept (a‘) and slope (b’) of a log-linear model, ln ψ =a‘+b’&thetas;, are also linearly related and an alternate form of the one-parameter model (LLM) can be derived, ln ψ, =p‘+b’(&thetas; +q‘), which uses AWC directly. The errors with this model are comparable to GHM. Unfortunately, LLM requires individual soilp’andq‘values and, because of more scatter in the intercept - slope relationship, pooledp’andq‘values for a group of soils are not as effective in LLM as they are in GHM.